Method for separating a volume of composite liquid into at least two components

ABSTRACT

A method for separating a volume of a composite liquid into at least a first component and a second component is performed in a centrifuge cooperating with a separation bag containing the volume of composite liquid. The separation bag is connected to at least a first component bag and a second component bag. The separation bag is spun so as to centrifuge the volume of composite liquid and cause the sedimentation of the at least first and second components. When the at least first and second components have sedimented, the first component is transferred at least one first transfer flow rate into the first component bag. When the first component has been transferred into the first component bag, the second component is transferred into the intermediate component bag at least one second transfer flow rate that is different from the at least one first transfer flow rate.

CROSS REFERENCE TO PRIOR APPLICATIONS

The present patent application is a divisional of U.S. patentapplication Ser. No. 10/783,831, filed Feb. 20, 2004, now U.S. Pat. No.7,347,932 which is a continuation in part of U.S. patent applicationSer. No. 10/648,559 filed on Aug. 25, 2003, now U.S. Pat. No. 7,166,217.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an apparatus and a method forseparating a volume of composite liquid into at least two components.

The apparatus and a method of the invention are particularly appropriatefor the separation of biological fluids comprising an aqueous componentand one or more cellular components. For example, potential uses of theinvention include: extracting a platelet component and a red blood cellcomponent from a volume of filtered blood obtained by flowing of avolume of whole blood through a filter removing platelets and whiteblood cells therefrom; extracting a plasma component, a plateletcomponent and a red blood cell component from a volume of filtered bloodobtained by flowing a volume of whole blood through a filter removingwhite blood cells therefrom; extracting a plasma component an a cellularcomponent (including platelets white blood cells, and red blood cells)from a volume of whole blood, the cellular component being subsequentlyfiltered so as to remove platelets and white blood cells therefrom;extracting a plasma component, a platelet component and a red blood cellcomponent from a volume of whole blood, the white blood cells beingsubsequently removed by filtration from the platelet component and thered blood cell component.

2. Description of the Related Art

An apparatus for processing blood components is known from document WO03/089027. This apparatus comprises a centrifuge adapted to cooperatewith an annular separation bag connected to at least one product bag,e.g. a platelet component bag. The centrifuge includes: a rotor having aturntable for supporting the separation bag, and a central compartmentfor containing the product bag connected to the separation bag; and asqueezing system for squeezing the separation bag and causing thetransfer of a separated component (e.g. platelets suspended in adiluting solution) from the separation bag into the product bag.

An object of the present invention is to design a centrifugationapparatus that can perform an optimized separation process forseparating, in a minimum amount of time, a composite fluid, such aswhole blood, into at least two high quality components.

SUMMARY OF THE INVENTION

According to the invention, an apparatus for separating a volume ofcomposite liquid into at least a first component and a second componentcomprises: a centrifuge having: a rotor comprising: a turntable forsupporting a flexible separation bag containing the volume of compositeliquid; and a central compartment for containing at least a firstcomponent bag and an second component bag connected to the separationbag; a squeezing member for squeezing the separation bag and causing thetransfer of the first component from the separation bag into the firstcomponent bag and the transfer of the second component from theseparation bag into the second component bag; a memory for storing atleast one centrifugation speed allowing for the sedimentation of the atleast first and second components in the separation bag, and informationrelated to at least one first transfer flow rate of the first componentinto the first component bag and at least one second transfer flow rateof the second component into the second component bag, whereby the atleast one first transfer flow rate and the at least one second transferflow rate are different; and a control unit programmed; for receivingfrom the memory the at least one centrifugation speed and theinformation related to the at least one first transfer flow rate and theat least one second transfer flow rate; and for causing the rotor torotate at the at least one centrifugation speed; and for causing, aftersedimentation of the at least first and second components in theseparation bag, the squeezing member to squeeze the separation bag so asto transfer the first component from the separation bag into the firstcomponent bag at the at least one first transfer flow rate, and totransfer the second component from the separation bag into the secondcomponent bag at the at least one second transfer flow rate.

More specifically, an apparatus for separating a volume of compositeliquid into a first component, an intermediate component including asecond component, and a third component comprises: a centrifuge having:a rotor comprising: a turntable for supporting a separation bagcontaining the volume of composite liquid; and a central compartment forcontaining at least a first component bag and an intermediate componentbag connected to the separation bag; a squeezing member for squeezingthe separation bag and causing the transfer of at least one portion ofthe first component from the separation bag into the first component bagand the transfer of the intermediate component from the separation baginto the intermediate component bag; a memory for storing at least onecentrifugation speed allowing for the sedimentation of the first, thesecond and the third components in the separation bag, and informationrelated to at least one first transfer flow rate of the first componentinto the first component bag and at least one second transfer flow rateof the intermediate component into the intermediate component bag,whereby the at least one first transfer flow rate and the at least onesecond transfer flow rate are different; and a control unit programmed:for receiving from the memory the at least one centrifugation speed andthe information related to the at least one first transfer flow rate andthe at least one second transfer flow rate; and for causing the rotor torotate at the at least one centrifugation speed; and for causing, aftersedimentation of the first, the second and the third components in theseparation bag, the squeezing member to squeeze the separation bag so asto transfer the at least one portion of the first component from theseparation bag into the first component bag at the at least one firsttransfer flow rate, and to transfer the intermediate component from theseparation bag into the intermediate component bag at the at least onesecond transfer flow rate.

Other features of the apparatus according to the invention are asfollows:

The squeezing member is further for causing the transfer of the thirdcomponent into a third component bag connected to the separation bag;the memory is further for storing information related to at least onethird transfer flow rate of the third component into the third componentbag, whereby the at least one third transfer flow rate is different fromthe at least one second transfer flow rate; and the control unit isfurther programmed: for receiving from the memory the informationrelated to the at least one third transfer flow rate; and for causingthe squeezing member to squeeze the separation bag so as to transfer thethird component from the separation bag into the third component bag atthe at least one third transfer flow rate.

The at least one first transfer flow rate is a substantially constantflow rate.

The at least one second transfer flow rate comprises an initial flowrate and a final flow rate, the final flow rate being lower than theinitial flow rate.

The at least one third transfer flow rate comprises an initial flow rateand a final flow rate, the final flow rate being lower than the initialflow rate.

In a first variant of the invention, the control unit is furtherprogrammed: for causing, upon sedimentation of the first, second, andthird components in the separation bag, the squeezing member to squeezethe separation bag so as to transfer a first portion of the firstcomponent from the separation bag into the first component bag at the atleast one first transfer flow rate, while a second portion of the firstcomponent remains in the separation bag; and for causing, after thetransfer of the first portion of the first component into the firstcomponent bag, a variation of the centrifugation speed so as to mix thesecond component with the second portion of the first component and formthe intermediate component.

In the first variant of the invention, the control unit is furtherprogrammed for causing the rotor to rotate at a first centrifugationspeed during the transfer of the first portion of the first componentfrom the separation bag into the first component bag; and causing arapid decrease of the centrifugation speed from the first centrifugationspeed to a second centrifugation speed so as to mix the second componentwith the second portion of the first component and form the intermediatecomponent.

Alternately, in a second variant of the invention, the control unit isfurther programmed: for causing, upon sedimentation of the first, secondand third components in the separation bag, the squeezing member tosqueeze the separation bag so as to transfer a first portion of thefirst component from the separation bag into the first component bag atthe at least one first transfer flow rate while a second portion of thefirst component remains in the separation bag; for causing, after thetransfer of the first portion of the first component into the firstcomponent bag, a rapid decrease in the centrifugation speed from a firstcentrifugation speed to a second centrifugation speed so as to cause amixing of the second component with the second portion of the firstcomponent and the third component; and for causing, after the mixing ofthe second component with the second portion of the first component andthe third component, an increase in the centrifugation speed from thesecond centrifugation speed to a third centrifugation speed so as toseparate the third component from an intermediate component comprisingthe second component and the second portion of the first component.

The control unit is further programmed for causing a transfer of airfrom the separation bag into one of the component bags before thetransfer of the first component from the separation bag into the firstcomponent bag.

The apparatus further comprises: a first valve member mounted on therotor for interacting with a first tube connecting the separation bag tothe first component bag and selectively allowing or blocking a flow offirst component therethrough; a second valve member mounted on the rotorfor interacting with a second tube connecting the separation bag to theintermediate component bag and selectively allowing or blocking a flowof intermediate component therethrough; and a third valve member mountedon the rotor for interacting with a third tube connecting the separationbag to the third component bag and selectively allowing or blocking aflow of fluid component therethrough, wherein the control unit isfurther programmed for controlling the first, the second and the thirdvalve members.

The apparatus further comprises: a first sensor for detecting the thirdcomponent on a pathway of the intermediate component to the intermediatecomponent bag; a second sensor for detecting the third component on apathway of the intermediate component to the intermediate component bagupstream of the first sensor; and a third sensor for detecting the thirdcomponent on a pathway of the first component to the first componentbag.

The control unit is further programmed for causing the transfer of theat least one portion of the first component from the separation bag intothe first component bag by causing: the first valve member to open; thesecond and third valve members to close; and the squeezing member tosqueeze the separation bag until the third sensor detects the thirdcomponent on a pathway of the first component to the first componentbag.

The control unit is further programmed for causing the transfer of theintermediate component from the separation bag into the intermediatecomponent bag by causing: the second valve member to open; the first andthird valve members to close; and the squeezing member to squeeze theseparation bag until the first sensor detects the third component on apathway of the intermediate component to the intermediate component bag.

The control unit is further programmed for causing the transfer of theintermediate component at the initial flow rate until the second sensordetects the third component and at the final flow rate until the firstsensor detects the third component.

The control unit is further programmed for causing the transfer of thethird component from the separation bag into the third component bag bycausing: the third valve member to open; the first and the second valvemembers to close; and the squeezing member to squeeze the separation baguntil it is substantially empty.

The first sensor is also adapted to detect a liquid on a pathway fromthe separation bag to the third component bag, and the control unit isfurther programmed for causing a transfer of air from the separation baginto the third component bags by causing: the first and second valvemembers to close; the third valve member to open; and the squeezingmember to squeeze the separation bag until the first sensor detects thefirst component.

The apparatus further comprises a lid that can be secured on theturntable for enclosing the flexible separation bag and the squeezingmember comprises: a flexible diaphragm secured to the turntable, apumping station for pumping a hydraulic fluid into and out of anexpandable chamber delimited between the turntable and the flexiblediaphragm, whereby the flexible separation bag is being squeezed againstthe lid when the hydraulic fluid is pumped into the expandable chamber;and a pressure sensor for sensing the pressure of the hydraulic fluidand detecting when the separation bag is substantially empty.

The control unit is further programmed for causing the transfer of thethird component at a first flow rate until the hydraulic pressuremeasured by the pressure sensor reaches a determined pressure threshold,and at a second flow rate after the hydraulic pressure measured by thepressure sensor has reached the determined pressure threshold, thesecond flow rate being lower than the first flow rate.

According to the invention, a method for separating a volume of acomposite liquid into at least a first component and a second componentcomprises the steps of: spinning a separation bag containing the volumeof composite liquid so as to centrifuge the volume of composite liquidand cause the sedimentation of the at least first and second components;when the at least first and second components have sedimented,transferring at least one first transfer flow rate the first componentinto a first component bag connected to the separation bag; when thefirst component has been transferred into the first component bag,transferring at least one second transfer flow rate the second componentinto a second component bag connected to the separation bag, whereby theat least one first and at least one second transfer flow rates aredifferent.

More specifically, a method for separating a volume of a compositeliquid into a first component, an intermediate component including asecond component, and a third component comprises the steps of: spinninga separation bag containing the volume of composite liquid at least onecentrifugation speed so as to centrifuge the volume of composite liquidand cause the sedimentation of the first, second and third components;when the three components have sedimented, transferring at least onefirst transfer flow rate at least one portion of the first componentinto a first component bag connected to the separation bag; when the atleast one portion of the first component has been transferred into thefirst component bag, transferring at least one second transfer flow ratethe intermediate component into an intermediate component bag connectedto the separation bag, whereby the at least one first and at least onesecond transfer flow rates are different.

Other features of the method according to the invention are as follows:

The method further comprises the step of transferring the thirdcomponent from the separation bag into a third component bag connectedto the separation bag at least one third transfer flow rate, whereby theat least one third transfer flow rate is different from the at least onesecond transfer flow rate.

The at least one first the transfer flow rate is a substantiallyconstant flow rate.

The at least one second transfer flow rate comprises an initial flowrate and a final flow rate, the final flow rate being lower than theinitial flow rate.

The at least one third transfer flow rate comprises an initial flow rateand a final flow rate, the final flow rate being lower than the initialflow rate.

The step of transferring the intermediate component into theintermediate component bag comprises the steps of: transferring theintermediate component into the intermediate component bag at theinitial flow rate until the third component is detected at a firstlocation on a pathway of the intermediate component to the intermediatecomponent bag; and transferring the intermediate component into theintermediate component bag at the final flow rate until the thirdcomponent is detected at a second location on a pathway of theintermediate component to the intermediate component bag, the firstlocation being upstream of the second location.

The step of transferring at least one portion of the first componentcomprises transferring a first portion of the first component from theseparation bag into the first component bag, while a second portion ofthe first component remains in the separation bag.

The method further comprises the step of mixing the second componentwith the second portion of the first component so as to form theintermediate component, after the transfer of the first portion of thefirst component into the first component bag.

In a first variant of the invention, the step of mixing the secondcomponent with the second portion of the first component comprisesrapidly decreasing the centrifugation speed from a first centrifugationspeed to a second centrifugation speed.

In a second variant of the invention, the step of mixing of the secondcomponent with the second portion of the first component comprises:rapidly decreasing the centrifugation speed from a first rotation speedto a second centrifugation speed that is substantially lower than thefirst centrifugation speed so as mix the second portion of the firstcomponent with the second component and the third component; andincreasing the centrifugation speed from the second rotation speed to athird centrifugation speed that is lower than the first centrifugationspeed so as to separate the first component from a mix of the secondcomponent with the second portion of the first component forming theintermediate component.

The method further comprises the step of transferring air from theseparation bag into one of the component bags before transferring thefirst component from the separation bag into the first component bag.

The step of transferring the first component from the separation baginto the first component bag comprises: allowing a flow of the firstcomponent through a first tube connecting the separation bag to thefirst component bag; blocking a flow of the intermediate componentthrough a second tube connecting the separation bag to the intermediatecomponent bag; blocking a flow of the third component through a thirdtube connecting the separation bag to the third component bag; andsqueezing the separation bag until the third component is detected on apathway of the first component to the first component bag.

The step of transferring the intermediate component from the separationbag into the intermediate component bag comprises: blocking a flow ofthe first component through a first tube connecting the separation bagto the first component bag; allowing a flow of the intermediatecomponent through a second tube connecting the separation bag to theintermediate component bag; blocking a flow of the third componentthrough a third tube connecting the separation bag to the thirdcomponent bag; and squeezing the separation bag until the thirdcomponent is detected on a pathway of the intermediate component to theintermediate component bag.

The step of transferring the third component from the separation baginto the third component bag comprises: blocking a flow of the firstcomponent through a first tube connecting the separation bag to thefirst component bag; blocking a flow of the intermediate componentthrough a second tube connecting the separation bag to the intermediatecomponent bag; allowing a flow of the third component through a thirdtube connecting the separation bag to the third component bag; andsqueezing the separation bag until it is substantially empty.

The step of squeezing the separation bag comprises: submitting theseparation bag to a hydraulic pressure; and measuring the hydraulicpressure, wherein the step of transferring the third component from theseparation bag into the third component bag comprises: transferring thethird component at a first flow rate until the measured hydraulicpressure reaches a determined pressure threshold; and transferring thethird component at a second flow rate after the measured hydraulicpressure has reached the determined pressure threshold, the second flowrate being lower than the first flow rate.

The method further comprises the step of transferring air from theseparation bag into the third component bag before transferring thefirst component from the separation bag into the first component bag,said step comprising: blocking a flow of the first component through afirst tube connecting the separation bag to the first component bag;blocking a flow of the intermediate component through a second tubeconnecting the separation bag to the intermediate component bag;allowing a flow of the third component through a third tube connectingthe separation bag to the third component bag; and squeezing theseparation bag until a liquid is detected on a pathway of the firstcomponent to the third component bag.

Other features and advantages of the invention will appear from thefollowing description and accompanying drawings, which are to beconsidered exemplary only.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a schematic view of set of separation and collection bagsdesigned for cooperating with a separation apparatus according to theinvention;

FIG. 2 is a top plan view of a separation bag designed for cooperatingwith a separation apparatus according to the invention;

FIG. 3 is a schematic view, partly in cross-section, of a separationapparatus according to the invention;

FIG. 4 is a cross-section view of the rotor of a separation apparatusaccording to the invention; and

FIG. 5 is a perspective view of the upper part of the rotor of theseparation apparatus of FIG. 4.

DETAILED DESCRIPTION

For the sake of clarity, the invention will be described with respect toa specific use, namely the separation of whole blood into a firstcomponent comprising plasma, a second component comprising platelets anda third component comprising red blood cell. It should be understoodhowever that this specific use is exemplary only.

A set of separation bags adapted to the separation of whole blood into aplasma product, a platelet product and red blood cell product is shownin FIG. 1. This set comprises a separation bag 1 and three product bags2, 3, 4. The separation bag 1 is annular and has outer circular edge 5and an inner circular edge 6. Variants of the separation bag include oneor two radial walls extending from the inner edge 6 to the outer edge 5so that the chamber defined within the bag, instead of being annular,has a C-shape with the C being more or less open. Also the separationbag can be shaped so as to fit either on a flat support surface or on afrusto-conical support surface of the rotor of a centrifuge. The firstproduct bag 2, intended for containing the plasma product, is connectedby a first tube 7 to the separation bag 1, at the inner edge 6 thereof.The second product bag 3, intended for containing the platelet product,is connected by a second tube 8 to the separation bag 1, at the inneredge 6 thereof. The third product bag 4, intended for containing the redblood cell product, is connected by a third tube 9 to the separation bag1, at the inner edge 6 thereof. It is connected to a secondary bag 10 bya tube 11 having two segments respectively connected to the inlet andthe outlet of a leukoreduction filter 12 (a filter for removing whiteblood cells). The secondary bag 10 contains a volume of storage solutionfor red blood cells. A plug 13 removable from within the secondary bag10 (so-called “frangible pin”, for example) blocks a liquid flow throughthe connecting tube 11 and prevents the storage solution from flowinginto the third product bag 4. The bag set further comprises a supplytube 14 that is connected at one end to the separation bag 1, at theinner edge thereof. The other end of the supply tube 14 is eitherconnected to a cannula, in which case the volume of blood to beseparated is to be directly drawn from a donor into the separation bag1, or connected directly or through a sterile connector 15 to acollection bag 16 connected in turn to a cannula 17 by a donor tube 18(as shown in FIG. 1). The bag into which a volume of blood from a donoris to be directly transferred (the separation bag 1 or the collectionbag 16) contains a volume of anti-coagulant solution (typically about 70ml of a solution of sodium citrate for a blood donation of about 450ml).

FIG. 2 shows a separation bag 1, which is made of two superposed sheetsof a flexible plastic material that are joined together by welded linesdefining an annular chamber 20 communicating with an inner semi-circulardistribution channel 21 via a narrow passage 22. More specifically, theannular chamber 20 is defined by a first circular welded line forming anouter edge 5, and a second circular welded line forming an inner edge 6,the two circular lines being substantially concentric. The distributionchannel 21 is defined by two substantially parallel and semi-circularwelded lines, forming an outer edge 23 and an inner edge 24 of thedistribution channel 21. The inner edge 6 of the annular chamber and theouter edge 24 of the distribution channel 21 join in two points anddefine therebetween the passage 22. The inner edge 6 of the annularchamber 20 inwardly converges towards both junction points, and theresulting concavity in the otherwise circular inner edge 6 of theannular channel 20 defines a triangular bay area 25 in the annularchamber 20 just upstream of the passage 22.

The passage 22 opens in the distribution channel 21 at about two thirdof the length of the channel. With respect to the passage 22, thedistribution channel 21 can therefore be defined as comprising a longersegment and a smaller segment that are interconnected and extend inopposite directions from the passage 22. The tube 9 connecting theproduct bag 4 for a red blood cell product to the separation chamber 1is connected to the smaller segment of the channel 21, at the endthereof. The tube 8 connecting the product bag 3 for a platelet productto the separation chamber 1 is connected to the longer segment of thechannel 21, at the end thereof. The tube 7 connecting the product bag 2for a plasma product to the separation chamber 1 is connected to thelonger segment of the channel 21, at about half of its length. The tube14 for connecting a source of whole blood (donor or collection bag 16)to the separation bag 1 is connected to the annular chamber 1 at theinner edge 6 thereof, at about one third of the circumference of theinner edge 6 from the passage 22, in the same direction as the directionin which the small segment of the distribution channel 21 extends.

The distribution channel 21 and an end portion of the tubes 7, 8, 9, 14are embedded in a disk-shaped support 26 made of a sheet of semi rigidplastic material, which is secured at its periphery to the inner edge 6of the annular chamber 20. The disk-shaped support 26 comprises a largecut-out in the middle thereof, as well as three small circular cut-outs28, 29, 30 adjacent to the connecting points of the tubes 7, 8, 9 to thedistribution channel 21. The circular cut-outs 28, 29, 30 are positionedwith respect to the end portion of tubes 7, 8, 9 so that each tubeextends along a diameter of the corresponding circular cut-out and istherefore maintained straight over a portion of its length by thedisk-shaped support 26.

FIGS. 3, 4, 5 show an apparatus for separating a volume of compositeliquid by centrifugation. The apparatus comprises a centrifuge adaptedfor receiving the set of separation and product bags shown in FIGS. 1and 2, and a squeezing system for squeezing the separation bag andcausing the transfer of separated components into the product bags.

The centrifuge comprises a rotor that is supported by a bearing assembly33 allowing the rotor to rotate about a vertical central axis 34. Therotor comprises a cylindrical rotor shaft 35, 36, a cylindricalcontainer 37 that is connected to the rotor shaft 35, 36 at the upperend thereof so that the longitudinal axis of the rotor shaft 35, 36 andthe longitudinal axis of the container 37 are aligned with the centralaxis 34 of the rotor, and a circular turntable 38 connected to thecontainer 37 at the upper end thereof so that the central axis of theturntable 37 is aligned with the central axis 34 of the rotor. The rotorshaft comprises a first upper portion 35 and a second lower portion 36.The upper portion 35 of the shaft extends in part through the bearingassembly 33. A pulley 39 is connected to the lower end of the upperportion 35 of the shaft.

The centrifuge further comprises a motor 40 coupled to the rotor by abelt 41 engaged in a groove of the pulley 39 so as to rotate the rotorabout the central vertical axis 34.

The separation apparatus further comprises three pinch valve members 42,43, 44 that are mounted on the rotor for selectively blocking orallowing a flow of liquid through a plastic tube, and selectivelysealing and cutting a plastic tube. Each valve 42, 43, 44 comprises anelongated cylindrical body and a head having a groove that is defined bya stationary upper jaw and a lower jaw movable between an open and aclosed position, the groove being dimensioned so that one of the plastictubes 7, 8, 9 of the bag set shown in FIGS. 1 and 2 can be snugglyengaged therein when the lower jaw is in the open position. Theelongated body contains a solenoid-actuated mechanism for moving thelower jaw and a radio frequency generator for providing the energy thatis necessary for sealing and cutting a plastic tube. The pinch valvemembers 42, 43, 44 are mounted inside the cylindrical container 37,adjacent the interior surface thereof, so that their longitudinal axisis parallel to the central axis 34 of the rotor and their heads protrudeabove the rim of the container 37. The three circular cut-outs 28, 29,30 of the support portion 26 of the separation bag 1 shown in FIG. 2 areso dimensioned and positioned as to allow for the engagement of theheads of the three pinch valve members 42, 43, 44 therethrough, with theportions of the tubes 7, 8, 9 extending across the circular cut-outs 28,29, 30 oriented so as to face the groove in the heads of the pinch valvemembers 42, 43, 44. Electric power is supplied to the pinch valvemembers 42, 43, 44 through a slip ring 45 that is mounted around thelower portion 36 of the rotor shaft.

The turntable 38 comprises a central frusto-conical portion 46, theupper, smaller edge of which is connected to the rim of the container37, an annular flat portion 47 connected to the lower, larger edge ofthe frusto-conical portion 46 and an outer cylindrical flange 48extending upwards from the outer periphery of the annular portion 47.The turntable 38 further comprises a vaulted circular lid 49 that issecured to the flange 48 by a hinge 50 so as to pivot between an openand a closed position. The lid 49 is fitted with a lock 51 by which itcan be blocked in the closed position. The lid 49 comprises a largecut-out 52 in its upper part that gives access to the cylindricalcontainer 37 of the rotor. The lid 49 has an annular interior surfacethat is so shaped that, when the lid 49 is in the closed position, itdefines with the frusto-conical portion 46 and the annular flat portion47 of the turntable 38 a frusto-conical annular compartment 53 having aradial cross-section that has substantially the shape of aparallelogram. The frusto-conical annular compartment 53, later the“separation compartment”, is intended for containing the separationchamber of the separation bag shown in FIG. 2.

The squeezing system for squeezing the separation bag within theseparation compartment 53 and causing the transfer of separatedcomponents into the product bags comprises a flexible annular diaphragm54 that is so shaped as to line the frusto-conical portion 46 and theannular flat portion 47 of the turntable 38, to which it is secured bygluing along its smaller and larger circular edges. The squeezing systemfurther comprises a hydraulic pumping station 31 for pumping a hydraulicliquid in and out an expandable hydraulic chamber 32 defined between theflexible diaphragm 54 and the turntable 38, via a duct 55 extendingthrough the rotor from the lower end of the lower portion 36 of therotor shaft to the turntable 38. The pumping station 31 comprises apiston pump having a piston 56 movable in a hydraulic cylinder 57fluidly connected via a rotary fluid coupling 58 to the rotor duct 55.The piston 56 is actuated by a stepper motor 59 that moves a lead screw60 linked to the piston rod. The hydraulic cylinder 57 is also connectedto a hydraulic liquid reservoir 61 having an access controlled by avalve 62 for selectively allowing the introduction or the withdrawal ofhydraulic liquid into and from a hydraulic circuit including thehydraulic cylinder 57, the rotor duct 55 and the expandable hydraulicchamber 32. A pressure gauge 63 is connected to the hydraulic circuitfor measuring the hydraulic pressure therein.

The separation apparatus further comprises three sensors 64, 65, 66 fordetecting characteristics of the separation process occurring within aseparation bag when the apparatus operates. The three sensors 64, 65, 66are embedded in the lid 49 so as to face the separation bag 1 as shownin FIG. 2, when the lid 49 is closed. The first sensor 64 (later the“channel sensor”) is embedded in the lid 49 so as to be positioned overthe longer segment of the distribution channel 21. The channel sensor 64is able to detect the presence of absence of liquid in the distributionchannel 21 as well as to detect red blood cells in a liquid. The secondsensor 65 (later the “bay sensor”) is embedded in the lid 49 so as to bepositioned over the bay area 25. The bay sensor 65 is able to detect redblood cells in a liquid. The third sensor 66 (later the “bag sensor”) isembedded in the lid 49 so as to be positioned over the separationchamber 20, at about one third of the breadth of the separation chamberfrom the inner edge 6 of the separation chamber 20, slightly outside ofthe bay area 25 on the side of the smaller segment of the distributionchannel 21. The bag sensor 66 is able to detect red blood cells in aliquid. Each sensor 64, 65, 66 can comprise a photocell including aninfra-red LED and a photo-detector.

The separation apparatus further comprises a controller 67 including amicroprocessor and a memory for providing the microprocessor withinformation and programmed instructions relative to the operation of theapparatus. In particular, the microprocessor is programmed for receivinginformation relative to the various centrifugation speeds at which therotor is to be rotated during the various stage of a separation process,and information relative to the various transfer flow rates at whichseparated components are to be transferred from the separation bag 1into the products bags 2, 3, 4. The information relative to the varioustransfer flow rates can be expressed, for example, as hydraulic liquidflow rates in the hydraulic circuit, or as rotation speeds of thestepper motor 59 of the hydraulic pumping station 31. The microprocessoris further programmed to receive, directly or through the memory,information from the pressure gauge 63 and from the photocells 64, 65,66.

The microprocessor is further programmed for controlling the centrifugemotor 40, the stepper motor 59, and the pinch valve members 42, 43, 44so as to cause the separation apparatus to operate as follows.

First stage: the volume of anti-coagulated blood to be separated istransferred into the separation bag before or after the disposable setis loaded in the centrifugation apparatus according to one of thefollowing variants.

First variant: a volume of anti-coagulated blood to be separated (forexample about 500 ml) is transferred into the separation bag before thedisposable set is loaded in the centrifugation apparatus. After a clamphas been placed at the connection of each tubes 7, 8, 9 to theseparation bag 1, a volume of anti-coagulated blood contained in acollection bag 16 is transferred by gravity in to the separation bag 1.The tube 14 connecting the collection bag 16 to the separation bag issealed and cut. The separation bag 1 is fitted within the turntable 38,the tubes 8, 7, 9 are engaged in the pinch valve members 42, 44, 43, andthe product bags 2, 3, 4, and the secondary bag 10 are placed into thecontainer 37. The pinch valve members 42, 44, 43 are closed and theclamps on the tubes 7, 8, 9 are removed. Alternately, clamps are notplaced on tubes 7, 8, 9 when pressure frangible seals are provided inboth segments of the distribution channel 21 so as to preventcommunication between the product bags 2, 3, 4 and the separation bag 1as long as the pressure that builds within the separation bag during theoperation of the separation apparatus is not high enough to break thefrangible seals.

Second variant: same as the first variant, except that the separationbag 1, which contains a volume of anticoagulant, is directly connectedto a donor and the blood of the donor is directly drawn into theseparation bag 1, which is thus also used as a collection bag.

Second stage: the air present in the separation bag 1 is purged into theproduct bag 4 in which the red blood cell component is to be latertransferred.

The pinch valve members 42, 44 are closed and the pinch valve member 43in which the tube 9 is engaged is open. The rotor is set in motion bythe centrifuge motor 40 and its rotation speed increases steadily untilit rotates at a first, high centrifugation speed (for example, about3200 RPM). Before the rotor rotates at the first centrifugation speed,the pumping station 31 is actuated so as to pump hydraulic liquid at aconstant flow rate (for example, about 240 ml/min) into the hydraulicchamber 32 and consequently squeeze the separation bag 1. The airpresent in the separation bag 1 is expelled into the product bag 4 forthe red blood cell component. When the channel sensor 64 detects aliquid in the distribution channel 21, the pumping station 31 is stoppedand the pinch valve member 43 is closed.

When the distribution channel 21 of the separation bag 1 is initiallyclosed by frangible seals, the transfer of air from the separation bag 1into the product bag 4 occurs once the pressure building up in theseparation bag 1 is high enough to cause the frangible seals to break.

Note that, alternately, the air contained in the separation bag 1 couldbe expelled into either the product bag 2 for the plasma component orthe product bag 3 for the platelet component. It is however of interestto expel the air in the bag 4 for the red blood cell component becausethis will allow the red blood cell component to be later transferred bygravity from the product bag 4 into the secondary bag 10.

Third stage: the blood within the separation chamber is sedimented to adesired level.

At the onset of this stage, the three pinch valve members 42, 43 and 44are closed. The rotor is rotated at the first high centrifugation speed(for example, about 3200 RPM) for a predetermined period of time (forexample, about 220 seconds) that is selected so that, whatever thehematocrit of the volume of the blood initially transferred in theseparation chamber 1, the blood sediments therein at the end of theselected period to a point where the hematocrit of the outer annular redblood cell layer is about 90 and the inner annular plasma layer plasmadoes not substantially contain anymore cells, the platelets and thewhite blood cells occupying then an intermediary annular layer betweenthe red blood cell layer and the plasma layer.

Fourth stage: a first component (plasma component) is transferred intothe product bag 2.

At the onset of this stage, the three pinch valve members 42, 43, 44 areclosed. Throughout the fourth stage, the rotor is rotated at the firsthigh centrifugation speed (for example, about 3200 RPM). After apredetermined period of time after the bag sensor 66 has stoppeddetecting red blood cells, which can happen before the end of thepredetermined sedimentation period, the pinch valve member 44controlling the access to the plasma component bag 4 is opened and thepumping station 31 is actuated so as to pump hydraulic liquid at aconstant flow rate (for example, about 220 ml/min) into the hydraulicchamber 32 and consequently squeeze the separation bag 1 for apredetermined period of time so as to cause the transfer of a firstportion of the plasma into the product bag 2, whereas a second portionof the plasma (for example, about 60 ml) remains in the separation bag1.

The transfer flow rate of the plasma component (which is directlyrelated to the flow rate of the hydraulic fluid) is selected to be ashigh as possible without disturbing the platelet layer so as to avoidcontaminating the plasma component with platelets.

Fifth stage: an Intermediate component (platelet component) is preparedin the separation bag 1.

First variant: the pinch valve member 44 controlling the access to theplasma component bag 4 is open, and the pinch valve members 42, 43 areclosed. The rotation speed of the rotor is rapidly decreased from thefirst centrifugation speed to a second centrifugation speed (forexample, from about 3200 RPM to about 2000 RPM, within about 10 seconds)so as to form an intermediate component resulting from the suspension ofthe platelets into the second portion of the plasma, whereas the redblood cell layer and the suspended platelet layer remains substantiallyseparated.

Second variant: the three pinch valve members 42, 43, 44 are closed. Therotation speed of the rotor is rapidly decreased from the firstcentrifugation speed to a second centrifugation speed (for example, fromabout 3200 RPM to about 1000 RPM, within about 20 seconds) so as to mixthe red blood cells, the platelets and the second portion of the plasma.The rotation speed of the rotor is then increased from the secondcentrifugation speed to a third centrifugation speed, lower that thefirst centrifugation speed (for example, from about 1000 RPM to about2500 RPM), so as to separate in the separation bag 1 a red blood cellcomponent and an intermediate component comprising a suspension ofplatelets in plasma.

Sixth stage: the intermediate component (platelet component) istransferred into the product bag 3.

The pinch valve member 42 controlling the access to the plateletcomponent bag 4 is open and the pinch valve members 43, 44 are closed.The rotor is rotated at the second centrifugation speed (for example,about 2000 RPM, if the preceding stage is the first variant of the fifthstage) or at the third rotation speed (for example, about 2500 RPM, ifthe preceding stage is the second variant of the fifth stage). Thepumping station 31 is actuated so as to the pump hydraulic liquid at afirst flow rate into the hydraulic chamber 32 and consequently squeezethe separation bag 1 so as to cause the transfer the platelet componentinto the product bag 3. The first flow rate (for example, about 140ml/min) is substantially lower than the flow rate (for example, about220 ml/min) at which the plasma component is transferred into theproduct bag 2 in the fourth stage. The first transfer flow rate of theplatelet component (which is directly related to the first flow rate ofthe hydraulic fluid) is selected to be high enough for preventing thesuspended platelets from sedimenting, without at the same timetriggering the activation of the platelets.

When the bay sensor 65 detects red blood cells, the pumping station 31is actuated so as to pump hydraulic liquid into the hydraulic chamber 32at a second flow rate (for example 40 ml/min) that is substantiallylower then the first flow rate, in order to prevent the contamination ofthe platelet component by red blood cells.

When the hydraulic liquid has been pumped into the hydraulic chamber 32at the second flow rate for a predetermined period of time (for example,about 4 seconds), the pumping station is actuated so as to pump thehydraulic liquid at a third flow rate (for example, about 20 ml/min)that is lower than the second flow rate, until a predetermined period oftime (for example, about 12 seconds) has lapsed after the channel sensor64 has detected red blood cells. The pumping station 31 is then stopped.

Seventh stage: the third component (red blood cell component) istransferred into the product bag 4.

The pinch valve member 43 controlling the access to the red blood cellcomponent bag 4 is open and the pinch valve members 42, 44 are closed.The rotation speed of the rotor is decreased from the secondcentrifugation speed (for example, about 2000 RPM) or the thirdcentrifugation speed (for example, about 2500 RPM) to a fourth, lower,centrifugation speed (for example, about 1500 RPM). The pumping station31 is actuated so as to pump hydraulic liquid at a first flow rate intothe hydraulic chamber 32 and consequently squeeze the separation bag 1so as to cause the transfer of the red blood cell component into theproduct bag 4. The first flow rate (for example, about 350 m/min) issubstantially higher than the flow rate (for example, about 220 ml/min)at which the plasma component is transferred into the product bag 2 inthe fourth stage. The first transfer flow rate of the red blood cellcomponent (which is directly related to the flow rate of the hydraulicfluid) is selected to be as high as possible without damaging the redblood cells (hemolysis).

When the pressure of the hydraulic liquid measured by the pressure gauge63 reaches a first high pressure threshold (for example, about 0.7 bar),the flow rate of the hydraulic liquid is decreased from the first flowrate to a second flow rate (for example, about 100 ml/min). When thepressure of the hydraulic liquid measured by the pressure gauge 63reaches a second high pressure threshold (for example, about 1.6 bar),the flow rate of the hydraulic liquid is further decreased from thesecond flow rate to a third flow rate (for example, about 37 ml/min).

The second and third transfer flow rates of the red blood cell component(which are directly related to the flow rate of the hydraulic fluid) areselected so that a maximal portion of the red blood cell component istransferred into the red blood cell component bag 4.

When a predetermined period of time (for example, about 30 seconds) haslapsed after the pressure of the hydraulic liquid has reached the secondpressure threshold, the rotation speed of the rotor is decreased untilthe rotor stops, the pumping station 31 is actuated so as to pump thehydraulic liquid from the hydraulic chamber 32 at a high flow rate (forexample, about 800 ml/min) until it the hydraulic chamber 32 is empty,and the three pinch valve members 42, 43, 44 are actuated so as to sealand cut the tubes 7, 8, 9.

Any of the at least one first transfer flow rate for the plasmacomponent (one flow rate in the example described above), the at leastone second transfer flow rate for the platelet component (threesuccessive flow rates in the example described above), the at leastthird first transfer flow rate for the red blood cell component (threesuccessive flow rates in the example described above) may besubstantially constant, as in the example described above, or it mayvary and, for example, comprise a ramp or a series of small steps.

It will be apparent to those skilled in the art that variousmodifications can be made to the apparatus and method described herein.Thus, it should be understood that the invention is not limited to thesubject matter discussed in the specification. Rather, the presentinvention is intended to cover modifications and variations.

1. A method for separating a volume of a composite liquid into a firstcomponent, an intermediate component including a second component, and athird component, whereby the volume of composite liquid is contained ina separation bag connected to at least a first component bag and anintermediate component bag, the method comprising the steps of: spinningthe separation bag at least one centrifugation speed so as to centrifugethe volume of composite liquid and cause the sedimentation of the first,second and third components; when the three components have sedimented,transferring at least one first transfer flow rate at least one portionof the first component into the first component bag; when the at leastone portion of the first component has been transferred into the firstcomponent bag, transferring at least one second transfer flow rate theintermediate component into the intermediate component bag, whereby theat least one first and at least one second transfer flow rates aredifferent.
 2. A method according to claim 1, wherein the at least onefirst the transfer flow rate is a substantially constant flow rate.
 3. Amethod according to claim 1, wherein the at least one second transferflow rate comprises an initial flow rate and a final flow rate, thefinal flow rate being lower than the initial flow rate.
 4. A methodaccording to claim 3, wherein the step of transferring the intermediatecomponent into the intermediate component bag comprises the steps of:transferring the intermediate component into the intermediate componentbag at the initial flow rate until the third component is detected at afirst location on a pathway of the intermediate component to theintermediate component bag; and transferring the intermediate componentinto the intermediate component bag at the final flow rate until thethird component is detected at a second location on a pathway of theintermediate component to the intermediate component bag, the firstlocation being upstream of the second location.
 5. A method according toclaim 1, wherein the step of transferring at least one portion of thefirst component comprises transferring a first portion of the firstcomponent from the separation bag into the first component bag, while asecond portion of the first component remains in the separation bag. 6.A method according to claim 5, further comprising the step of mixing thesecond component with the second portion of the first component so as toform the intermediate component, after the transfer of the first portionof the first component into the first component bag.
 7. A methodaccording to claim 6, further comprising spinning the separation bag ata first centrifugation speed during the transfer of the first portion ofthe first component from the separation bag into the first componentbag.
 8. A method according to claim 7, wherein the step of mixing thesecond component with the second portion of the first componentcomprises rapidly decreasing the centrifugation speed from the firstcentrifugation speed to a second centrifugation speed.
 9. A methodaccording to claim 7, wherein the step of mixing of the second componentwith the second portion of the first component comprises: rapidlydecreasing the centrifugation speed from the first rotation speed to asecond centrifugation speed that is substantially lower than the firstcentrifugation speed so as mix the second portion of the first componentwith the second component and the third component; and increasing thecentrifugation speed from the second rotation speed to a thirdcentrifugation speed that is lower than the first centrifugation speedso as to separate the first component from a mix of the second componentwith the second portion of the first component forming the intermediatecomponent.
 10. A method according to claim 1, further comprising thestep of transferring air from the separation bag into one of thecomponent bags before transferring the first component from theseparation bag into the first component bag.
 11. A method according toclaim 1, wherein the step of squeezing the separation bag comprisessubmitting the separation bag to a hydraulic pressure.
 12. A methodaccording to claim 1, wherein the composite liquid comprises wholeblood, the first component comprises plasma, the second componentcomprises platelets, the third component comprise red blood cells andthe intermediate component comprises a suspension of platelets inplasma.
 13. A method according to claim 1, further comprising the stepof transferring the third component from the separation bag into a thirdcomponent bag connected to the separation bag at least one thirdtransfer flow rate, whereby the at least one third transfer flow rate isdifferent from the at least one second transfer flow rate.
 14. A methodaccording to claim 13, wherein the at least one third transfer flow ratecomprises an initial flow rate and a final flow rate, the final flowrate being lower than the initial flow rate.
 15. A method according toclaim 13, further comprising spinning the separation bag during thetransfer of the third component from the separation bag into the thirdcomponent bag at a centrifugation speed that is less than acentrifugation speed during the transfer of the intermediate componentinto the intermediate component bag.
 16. A method according to claim 13,wherein the step of transferring the first component from the separationbag into the first component bag comprises: allowing a flow of the firstcomponent through a first tube connecting the separation bag to thefirst component bag; blocking a flow of the intermediate componentthrough a second tube connecting the separation bag to the intermediatecomponent bag; blocking a flow of the third component through a thirdtube connecting the separation bag to the third component bag; andsqueezing the separation bag until the third component is detected on apathway of the first component to the first component bag.
 17. A methodaccording to claim 13, wherein the step of transferring the intermediatecomponent from the separation bag into the intermediate component bagcomprises: blocking a flow of the first component through a first tubeconnecting the separation bag to the first component bag; allowing aflow of the intermediate component through a second tube connecting theseparation bag to the intermediate component bag; blocking a flow of thethird component through a third tube connecting the separation bag tothe third component bag; and squeezing the separation bag until thethird component is detected on a pathway of the intermediate componentto the intermediate component bag.
 18. A method according to claim 13,wherein the step of transferring the third component from the separationbag into the third component bag comprises: blocking a flow of the firstcomponent through a first tube connecting the separation bag to thefirst component bag; blocking a flow of the intermediate componentthrough a second tube connecting the separation bag to the intermediatecomponent bag; allowing a flow of the third component through a thirdtube connecting the separation bag to the third component bag; andsqueezing the separation bag until it is substantially empty.
 19. Amethod according to claim 18, further comprising the steps of: detectingwhen the separation bag is substantially empty, and stopping spinningthe separation bag after detecting that the separation bag issubstantially empty.
 20. A method according the claim 13, wherein thestep of squeezing the separation bag comprises: submitting theseparation bag to a hydraulic pressure; and measuring the hydraulicpressure, wherein the step of transferring the third component from theseparation bag into the third component bag comprises: transferring thethird component at a first flow rate until the measured hydraulicpressure reaches a determined pressure threshold; and transferring thethird component at a second flow rate after the measured hydraulicpressure has reached the determined pressure threshold, the second flowrate being lower than the first flow rate.
 21. A method according toclaim 13, further comprising the step of transferring air from theseparation bag into the third component bag before transferring thefirst component from the separation bag into the first component bag,said step comprising: blocking a flow of the first component through afirst tube connecting the separation bag to the first component bag;blocking a flow of the intermediate component through a second tubeconnecting the separation bag to the intermediate component bag;allowing a flow of the third component through a third tube connectingthe separation bag to the third component bag; and squeezing theseparation bag until a liquid is detected on a pathway of the firstcomponent to the third component bag.
 22. A method for separating avolume of a composite liquid into at least a first component and asecond component, whereby the volume of composite liquid is contained ina separation bag connected to at least a first component bag and asecond component bag, the method comprising the steps of: spinning theseparation bag so as to centrifuge the volume of composite liquid andcause the sedimentation of the at least first and second components;when the at least first and second components have sedimented,transferring at least one first transfer flow rate the first componentinto the first component bag; when the first component has beentransferred into the first component bag, transferring at least onesecond transfer flow rate the second component into the second componentbag, whereby the at least one first and at least one second transferflow rates are different.
 23. A method according to claim 22, whereinthe composite fluid comprises whole blood, the first component comprisesplasma, and the second component comprises platelets.
 24. A methodaccording to claim 22, wherein the composite fluid comprises wholeblood, the first component comprises plasma, and the second componentcomprises red blood cells.